More than one-third of the world's population lives in areas at risk for transmission of dengue virus (DENV). Dengue virus is a flavivirus, in the same genus as West Nile virus and Yellow Fever virus. Dengue virus is a leading cause of illness in the tropics and subtropics, with as many as 100 million people infected yearly. Dengue is caused by any one of four related viral serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) transmitted by mosquitoes. It is critical that once dengue infection is detected, that prompt supportive treatment be administered. Infection may be asymptomatic or it may cause a spectrum of clinical syndromes ranging from self-limiting febrile illness to life-threatening severe dengue disease. Hundreds of thousands of clinical dengue disease cases are reported by clinicians annually to the WHO and dengue disease has a mortality rate of 0.5% to 5.0%. Any of the four serotypes can cause severe disease in humans and all four serotypes circulate globally. (Guy B and Almond J W, Comp Immunol Microbiol Infect Dis 31, 239-252 (2008); Guzman M G et al, Nat Rev Microbiol 8 S7-S16 (2010); Halstead S B, Lancet 370, 1644-1652 (2007); and Wilder-Smith et al Curr Infect Dis Rep 12, 157-164 (2011); all of which are incorporated by reference in their entireties.)